A is not correct. The colonists believed the slaves we're not intelligent to teach, but they let them teach their kids. B looks like a good answer. The did put big taxes on the owning and buying of slaves. C is kinda irrelevant to the question, haha. D is an "ugh" kind of answer because they didnt really need the slaves to follow their religion, but they did make them convert, most of them to at least. B looks like the best answer to be honest. They'd get money from the taxes they got from the slaves, since slaves were popular, it increased economy.
Your answers:
A.The colonists used slaves as teachers and doctors.
B.The colonies taxed the sale and ownership of slaves.
C.Slaves increased the number of citizens in the colonies.
D.The colonists converted slaves to their respective religions.